The invention is directed to a method wherein print data define the picture elements of a print image to be printed onto the carrier material. Water-based or solvent-based, chromatic fluids are employed as a printing fluid. The carrier material, for example, is white paper or plastic film. The print data contain one or more bit places per picture element. For example, the value one in a bit place indicates that a black picture element is to be printed. The value zero in a bit place indicates that no printing fluid is to be applied on the picture element. The picture element retains the color of the carrier material.
European Letters Patent EP 0 756 566 B1 discloses a thermoelectric printing unit for transferring an ink onto a recording medium. The printing unit contains a printing drum with print elements arranged matrix-like that respectively contain a depression for the acceptance of ink. The ink is introduced into the depressions from the outside. A heating element, with the assistance of which the ink is expelled upon vapor formation dependent on the print data, is located in each depression.
U.S. Pat. No. 4,275,290 discloses a thermoelectric ink printing unit wherein ink is heated in depressions, whereupon surface tension and volume change. The ink flows into widened portions arranged opposite a recording medium. A meniscus forming thereat inks the recording medium.
Further, U.S. Pat. No. 4,675,694 discloses a thermoelectric ink printing unit wherein solid ink is heated. After becoming molten, the ink expands and moistens a recording medium in character-dependent fashion.
DE-A1-19718906, which does not enjoy prior publication, likewise discloses a thermoelectric ink printing unit having a hollow drum with depressions arranged thereon in matrix-like fashion. A gas bubble is generated in the ink via a laser, whereupon the ink expands and moistens a recording medium.